RS232 Com Tap Data Monitor
is an inexpensive, compact, USB powered, all-in-one solution for RS232 data
monitoring. Can be used on PC's with no com ports (or any PC with USB ports) to
monitor full and half duplex RS232 communication. RS232 Com Tap comes with
drivers for just about any operating system, a 6ft(2m) USB cable and both the
newest registered copies or RS232 Hex Com Tool and RS232M Com Monitor.

These pages are a useful collection of
microcontroller RS-232 data acquisition circuits and code. Most of the code on
these pages is written in C because it is the language that is definitely the
fastest way to produce working applications.

For the people who are interested in these
circuits, the code will be available on the pages in C and hex. The hex file
code can be cut and pasted into an ascii text file with notepad or another text
editor and saved as "name.hex". If there is a
problem converting the hex file, please email us and we will send it out! (Not
all circuits have micro's or code).

Our reliable relay circuit and code can switch up to 8 independent relays. This inexpensive circuit
uses a 18-pin 16C54 microcontroller or any compatible PIC controller (with minor
code changes). We have code for Byte Craft and CCS compilers.
In the Byte Craft
compiler version 3 C files are provided
for the circuit, the main() file and transmit / receive routines. If you will be
using the C files, they must be in 3 separate files with the names
"relay.c", "rx12.c" and "tx12.c".
Program the chip with Watchdog = off.
This code was compiled with MpLab v4.99 and Bytecraft's MPC C compiler v1.31.
In the CCS compiler
version there is just one file. The code uses the built-in commands for the
RS232 functions. The Watchdog should also be programmed in the off state. MPLab
6.30 and CCS compiler version 3.1 were used for this project.
Use this circuit with the Virtual
Relay Control Panel. The VRCP is a windows app that allows you to open and
close the relays through your PC by clicking on each relay image. The VCRP
project has all the source code to build the app with C++ Builder. The EXE file
is included.

Build
a 4X4 Keypad circuit that transmits an ASCII character on an RS232 line every
time a key is pressed. The circuit shown can be used directly from a
microcontroller or add the RS232 interface circuit to control the LCD from
a PC.
The demo project can be compiled with Hi-tech's PIC or
Piclite C
compiler's
and our 9600 baud RS232 library.
This circuit uses an inexpensive Grayhill #96BB2-006-F (or similar) 4x4 keypad which can be purchased from Digikey.
There are many 4x4 keypads with the same pin-out. Download
the project here.

Build
a 2X16 RS232 LCD that can be controlled from a PC at RS232 signal levels or from
microcontroller levels. The circuit shown can be used directly from a
microcontroller or add the RS232 interface circuit to control the LCD from
a PC.
The demo project can be compiled with Hi-tech's PIC or
Piclite C
compiler's
and our 9600 baud RS232 library.
This circuit uses an Optrex DMC-16207U (or similar with 14/16-pin interface) LCD which can be purchased from Digikey
for <$20.Commands include: write char, write
string, cursor off, cursor
blink,
goto line 1, goto line 2, clear.
Download the the project with C files, hex file and lcd.scp script file for RS232
Hex Com Tool 4.0.
(RS232 library must be purchased to compile the project.)

RS-232
Virtual DVM circuit, an RS232 powered volt meter, no batteries, no power
supplies! The code was compiled with MpLab v4.99 and Bytecraft's MPC C compiler
v1.31.
Use this circuit with the DVM2000.
The DVM200 is a virtual windows app that shows the voltage at the input to the
circuit in a small window on the screen. The DVM2000 project has all the source
code to build the app with C++ Builder. The EXE file is included so C++ Builder
is not necessary.

Use this generic RS-232
interface circuit to connect a microcontroller to a PC. The maxium chip does
the electrical part of interfacing.
The RX and TX lines go to the micro and are wired for a straight through cable.
If you have or want to use a null modem cable, simply switch pins 2 and 3 on the
DB9 female connector. This circuit uses no handshaking.

Use this RS-232
indicator circuit to monitor the RX and TX line of the circuit above. This
circuit uses a 8-pin 12C508 microcontroller, made by Microchip and causes either
the TX led or the RX led to turn on for 1/3 of a second when it sees activity on
either line. Each led is independent of the other.
Program the chip for Internal Oscillator, MCLR = on, Watchdog = off.
This code was compiled with MpLab and Bytecraft's MPC C compiler.

Download
a documentation package to build a in circuit programmer / prototype
board for Philips Semiconductors new 8-bit, 8051 compatible, 89C51Rx+ and
89C51Rx2 microcontrollers with up to 64K ISP FLASH and 1K RAM. This board can be
used for other purposes by using the expansion connectors. You can build this
board for around $50.

Sometimes it is necessary to
isolate the peripheral circuit from the PC for noise or floating ground
situations. This circuit will
do the job. The circuit uses a DC/DC converter made by Power One, Inc. These
parts can be purchased from Digikey.

A very good C compiler with a good reputation. Comes with examples and built in
functions.
Write code for ALL microchip devices for under $500.00 or for most of the
micro's on this page for $125.